Pavlos Lazaridis - Academia.edu (original) (raw)
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Papers by Pavlos Lazaridis
2017 XXXIInd General Assembly and Scientific Symposium of the International Union of Radio Science (URSI GASS)
2018 2nd URSI Atlantic Radio Science Meeting (AT-RASC), 2018
Wireless Personal Communications, 2021
Massive MIMO will improve the performance of future 5G systems in terms of data rate and spectral... more Massive MIMO will improve the performance of future 5G systems in terms of data rate and spectral efficiency, while accommodating a large number of users. Furthermore, it allows for 3D beamforming in order to provide more degrees of freedom and increase the number of high-throughput users. Massive MIMO is expected to provide more advantages compared to other solutions in terms of energy and spectral efficiency. This will be achieved by focusing the radiation towards the direction of the intended users, thus implementing simultaneous transmission to many users while keeping interference low. It can boost the capacity compared to a conventional antenna solution, resulting in a spectral efficiency up to 50 times greater than that provided by actual 4G technology. However, to take full advantage of this technology and to overcome the challenges of implementation in a real environment, a complicated radio system is required. The purpose of this work is to present the MIMO technology evol...
Sensors, 2021
The lifespan assessment and maintenance planning of high-voltage power systems requires condition... more The lifespan assessment and maintenance planning of high-voltage power systems requires condition monitoring of all the operational equipment in a specific area. Electrical insulation of electrical apparatuses is prone to failure due to high electrical stresses, and thus it is a critical aspect that needs to be monitored. The ageing process of the electrical insulation in high voltage equipment may accelerate due to the occurrence of partial discharge (PD) that may in turn lead to catastrophic failures if the related defects are left untreated at an initial stage. Therefore, there is a requirement to monitor the PD levels so that an unexpected breakdown of high-voltage equipment is avoided. There are several ways of detecting PD, such as acoustic detection, optical detection, chemical detection, and radiometric detection. This paper focuses on reviewing techniques based on radiometric detection of PD, and more specifically, using received signal strength (RSS) for the localization o...
2018 IEEE International Symposium on Electromagnetic Compatibility and 2018 IEEE Asia-Pacific Symposium on Electromagnetic Compatibility (EMC/APEMC), 2018
Antennas and Propagation Conference 2019 (APC-2019), 2019
In this paper, particle swarm optimization is employed to carry out transmit antenna subgrouping ... more In this paper, particle swarm optimization is employed to carry out transmit antenna subgrouping algorithm for massive multiple input and multiple output (MIMO) system. A minimum number of transmit antenna elements are selected to achieve a similar quality of service (QoS) as that of a single user MIMO system. Simulation results show that our proposed algorithm achieves similar capacity performance as compared to massive MIMO systems when employing exhaustive search for transmit antenna selection.
2020 XXXIIIrd General Assembly and Scientific Symposium of the International Union of Radio Science, 2020
This paper presents a design of a printed log-periodic dipole array (PLPDA) antenna with large op... more This paper presents a design of a printed log-periodic dipole array (PLPDA) antenna with large operating frequency range from 0.4 GHz to 8 GHz. The proposed antenna design employs a triangular shaped longest dipole element. The triangular shape of the longest dipole element and optimization of the last four dipole element lengths, thicknesses and spacings between them significantly improves the low frequency response. The proposed antenna design provides low return loss demonstrating excellent matching of the antenna. The antenna also provides a reasonable gain of around 5.5 dBi and highly directional characteristics.
Electronics, 2021
This paper initially presents an overview of different miniaturization techniques used for size r... more This paper initially presents an overview of different miniaturization techniques used for size reduction of printed log-periodic dipole array (PLPDA) antennas, and then continues by presenting a design of a conventional PLPDA design that operates from 0.7–8 GHz and achieves a realized gain of around 5.5 dBi in most of its bandwidth. This antenna design is then used as a baseline model to implement a novel technique to extend the low-frequency response. This is completed by replacing the longest straight dipole with a triangular-shaped dipole and by optimizing the four longest dipoles of the antenna using the Trust Region Framework algorithm in CST. The improved antenna with extended low-frequency response operates from 0.4 GHz to 8 GHz with a slightly reduced gain at the lower frequencies.
2020 14th European Conference on Antennas and Propagation (EuCAP), 2020
Electronics, 2020
The coexistence of TV broadcasting and mobile services causes interference that leads to poor qua... more The coexistence of TV broadcasting and mobile services causes interference that leads to poor quality-of-service for TV consumers. Solutions usually found in the market involve external band-stop filters along with TV reception log-periodic and Yagi-Uda antennas. This paper presents a log-periodic antenna design without additional filtering that serves as a lower cost alternative to avoid interference from mobile services into the UHF TV. The proposed antenna operates in the UHF TV band (470–790 MHz-passband) and rejects the 800 MHz and 900 MHz bands (stopband) of 4G/LTE-800 and GSM900 services, respectively. Matching to 50 Ohms is very satisfactory in the passband with values of S11 below −12 dB. Furthermore, the antenna is highly directive with a realized gain of approximately 8 dBi and a front-to-back ratio greater than 20 dB.
Electronics, 2020
An aperiodic reconfigurable microstrip antenna array is designed to serve as a DVB-T base station... more An aperiodic reconfigurable microstrip antenna array is designed to serve as a DVB-T base station antenna operating in a single broadcasting channel. The antenna array is optimized at 698 MHz (center frequency of DVB-T channel 49) to concurrently achieve a particular radiation pattern shaping with high forward gain, main lobe tilting and null filling inside the service area, as well as low sidelobe level outside the service area, and low standing wave ratio at the inputs of all the array elements. To concurrently satisfy all the above requirements, both the geometry dimensions and the array feeding weights (amplitudes and phases) are optimized, thus leading to a complex multi-variable and multi-objective problem. The problem is solved by applying a recently developed particle swarm optimization (PSO) improved variant, called PSO with velocity mutation, in conjunction with the CST software package, which is employed by the PSOvm every time a full-wave analysis is required. Furthermor...
IEEE Sensors Journal, 2020
IEEE Transactions on Antennas and Propagation, 2020
Sensors, 2020
Regulatory requirements for sub-sea oil and gas operators mandates the frequent inspection of pip... more Regulatory requirements for sub-sea oil and gas operators mandates the frequent inspection of pipeline assets to ensure that their degradation and damage are maintained at acceptable levels. The inspection process is usually sub-contracted to surveyors who utilize sub-sea Remotely Operated Vehicles (ROVs), launched from a surface vessel and piloted over the pipeline. ROVs capture data from various sensors/instruments which are subsequently reviewed and interpreted by human operators, creating a log of event annotations; a slow, labor-intensive and costly process. The paper presents an automatic image annotation framework that identifies/classifies key events of interest in the video footage viz. exposure, burial, field joints, anodes, and free spans. The reported methodology utilizes transfer learning with a Deep Convolutional Neural Network (ResNet-50), fine-tuned on real-life, representative data from challenging sub-sea environments with low lighting conditions, sand agitation, s...
IEEE Transactions on Electromagnetic Compatibility, 2019
IEEE Transactions on Antennas and Propagation, 2019
IEEE Transactions on Antennas and Propagation, 2019
IEEE Transactions on Antennas and Propagation, 2018
2017 XXXIInd General Assembly and Scientific Symposium of the International Union of Radio Science (URSI GASS)
2018 2nd URSI Atlantic Radio Science Meeting (AT-RASC), 2018
Wireless Personal Communications, 2021
Massive MIMO will improve the performance of future 5G systems in terms of data rate and spectral... more Massive MIMO will improve the performance of future 5G systems in terms of data rate and spectral efficiency, while accommodating a large number of users. Furthermore, it allows for 3D beamforming in order to provide more degrees of freedom and increase the number of high-throughput users. Massive MIMO is expected to provide more advantages compared to other solutions in terms of energy and spectral efficiency. This will be achieved by focusing the radiation towards the direction of the intended users, thus implementing simultaneous transmission to many users while keeping interference low. It can boost the capacity compared to a conventional antenna solution, resulting in a spectral efficiency up to 50 times greater than that provided by actual 4G technology. However, to take full advantage of this technology and to overcome the challenges of implementation in a real environment, a complicated radio system is required. The purpose of this work is to present the MIMO technology evol...
Sensors, 2021
The lifespan assessment and maintenance planning of high-voltage power systems requires condition... more The lifespan assessment and maintenance planning of high-voltage power systems requires condition monitoring of all the operational equipment in a specific area. Electrical insulation of electrical apparatuses is prone to failure due to high electrical stresses, and thus it is a critical aspect that needs to be monitored. The ageing process of the electrical insulation in high voltage equipment may accelerate due to the occurrence of partial discharge (PD) that may in turn lead to catastrophic failures if the related defects are left untreated at an initial stage. Therefore, there is a requirement to monitor the PD levels so that an unexpected breakdown of high-voltage equipment is avoided. There are several ways of detecting PD, such as acoustic detection, optical detection, chemical detection, and radiometric detection. This paper focuses on reviewing techniques based on radiometric detection of PD, and more specifically, using received signal strength (RSS) for the localization o...
2018 IEEE International Symposium on Electromagnetic Compatibility and 2018 IEEE Asia-Pacific Symposium on Electromagnetic Compatibility (EMC/APEMC), 2018
Antennas and Propagation Conference 2019 (APC-2019), 2019
In this paper, particle swarm optimization is employed to carry out transmit antenna subgrouping ... more In this paper, particle swarm optimization is employed to carry out transmit antenna subgrouping algorithm for massive multiple input and multiple output (MIMO) system. A minimum number of transmit antenna elements are selected to achieve a similar quality of service (QoS) as that of a single user MIMO system. Simulation results show that our proposed algorithm achieves similar capacity performance as compared to massive MIMO systems when employing exhaustive search for transmit antenna selection.
2020 XXXIIIrd General Assembly and Scientific Symposium of the International Union of Radio Science, 2020
This paper presents a design of a printed log-periodic dipole array (PLPDA) antenna with large op... more This paper presents a design of a printed log-periodic dipole array (PLPDA) antenna with large operating frequency range from 0.4 GHz to 8 GHz. The proposed antenna design employs a triangular shaped longest dipole element. The triangular shape of the longest dipole element and optimization of the last four dipole element lengths, thicknesses and spacings between them significantly improves the low frequency response. The proposed antenna design provides low return loss demonstrating excellent matching of the antenna. The antenna also provides a reasonable gain of around 5.5 dBi and highly directional characteristics.
Electronics, 2021
This paper initially presents an overview of different miniaturization techniques used for size r... more This paper initially presents an overview of different miniaturization techniques used for size reduction of printed log-periodic dipole array (PLPDA) antennas, and then continues by presenting a design of a conventional PLPDA design that operates from 0.7–8 GHz and achieves a realized gain of around 5.5 dBi in most of its bandwidth. This antenna design is then used as a baseline model to implement a novel technique to extend the low-frequency response. This is completed by replacing the longest straight dipole with a triangular-shaped dipole and by optimizing the four longest dipoles of the antenna using the Trust Region Framework algorithm in CST. The improved antenna with extended low-frequency response operates from 0.4 GHz to 8 GHz with a slightly reduced gain at the lower frequencies.
2020 14th European Conference on Antennas and Propagation (EuCAP), 2020
Electronics, 2020
The coexistence of TV broadcasting and mobile services causes interference that leads to poor qua... more The coexistence of TV broadcasting and mobile services causes interference that leads to poor quality-of-service for TV consumers. Solutions usually found in the market involve external band-stop filters along with TV reception log-periodic and Yagi-Uda antennas. This paper presents a log-periodic antenna design without additional filtering that serves as a lower cost alternative to avoid interference from mobile services into the UHF TV. The proposed antenna operates in the UHF TV band (470–790 MHz-passband) and rejects the 800 MHz and 900 MHz bands (stopband) of 4G/LTE-800 and GSM900 services, respectively. Matching to 50 Ohms is very satisfactory in the passband with values of S11 below −12 dB. Furthermore, the antenna is highly directive with a realized gain of approximately 8 dBi and a front-to-back ratio greater than 20 dB.
Electronics, 2020
An aperiodic reconfigurable microstrip antenna array is designed to serve as a DVB-T base station... more An aperiodic reconfigurable microstrip antenna array is designed to serve as a DVB-T base station antenna operating in a single broadcasting channel. The antenna array is optimized at 698 MHz (center frequency of DVB-T channel 49) to concurrently achieve a particular radiation pattern shaping with high forward gain, main lobe tilting and null filling inside the service area, as well as low sidelobe level outside the service area, and low standing wave ratio at the inputs of all the array elements. To concurrently satisfy all the above requirements, both the geometry dimensions and the array feeding weights (amplitudes and phases) are optimized, thus leading to a complex multi-variable and multi-objective problem. The problem is solved by applying a recently developed particle swarm optimization (PSO) improved variant, called PSO with velocity mutation, in conjunction with the CST software package, which is employed by the PSOvm every time a full-wave analysis is required. Furthermor...
IEEE Sensors Journal, 2020
IEEE Transactions on Antennas and Propagation, 2020
Sensors, 2020
Regulatory requirements for sub-sea oil and gas operators mandates the frequent inspection of pip... more Regulatory requirements for sub-sea oil and gas operators mandates the frequent inspection of pipeline assets to ensure that their degradation and damage are maintained at acceptable levels. The inspection process is usually sub-contracted to surveyors who utilize sub-sea Remotely Operated Vehicles (ROVs), launched from a surface vessel and piloted over the pipeline. ROVs capture data from various sensors/instruments which are subsequently reviewed and interpreted by human operators, creating a log of event annotations; a slow, labor-intensive and costly process. The paper presents an automatic image annotation framework that identifies/classifies key events of interest in the video footage viz. exposure, burial, field joints, anodes, and free spans. The reported methodology utilizes transfer learning with a Deep Convolutional Neural Network (ResNet-50), fine-tuned on real-life, representative data from challenging sub-sea environments with low lighting conditions, sand agitation, s...
IEEE Transactions on Electromagnetic Compatibility, 2019
IEEE Transactions on Antennas and Propagation, 2019
IEEE Transactions on Antennas and Propagation, 2019
IEEE Transactions on Antennas and Propagation, 2018